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bài 8
c) chứng minh \(\overline{aaa}⋮37\)
ta có: \(aaa=a\cdot111\)
\(=a\cdot37\cdot3⋮37\)
\(\Rightarrow aaa⋮37\)
k mk nha
k mk nha.
#mon
1/
a. \(x^3-2=25\)
\(x^3=25+2\)
\(x^3=27\)
\(\Rightarrow x=3\)
b.\(\left(x-3\right)^2=25\)
\(\left(x-3\right)^2=5^2\)
\(\Rightarrow x-3=5\)
\(\Rightarrow x=8\)
1,a, x^3-2=25 b, (x-3)^2=25 c, x^3-x^2=55 d,[(8.x-12):4].3^7=3^10
x^3=27 (x-3)^2=5^2 không có giá trị x (8.x-12):4=3^3
x^3=3^3 x-3=5 8.x-12=108
x=3 x=8 8.x=120
x=15
2, a, \(7^6:7^4+3^4.3^2-3^7:3\) b, 1736-(21-16).32+6.7^2 c,56.17+17.44-4^3.5+6.(3^2-2)
=\(7^2+3^6-3^6\) =1736-5.32+6.49 =17.(56+44)-320+42
=\(49\) =1736-160+294 =17.10-278
=1736+134 =170-278
=1870 =-108
d, 3.10^2-[1200-(4^2-2.3)^3]
=300-[1200-(16-6)^3]
=300-(1200-10^3)
=300-(1200-1000)
=300-200
=100
707 - 3( x + 34 ) = 407
=> 3( x + 81 ) = 300
=> x + 81 = 100
=> x = 19
127 + 3( x + 17 ) = ( 47 : 45 )2
=> 3( x + 17 ) = ( 42 )2 - 127
=> 3( x + 17 ) = 256 - 127
=> 3( x + 17 ) = 129
=> x + 17 43
=> x = 26
x - 6 - ( 48 - 24. 2 : 6 - 3 ) = 100
x - 6 - ( 48 - 2 - 3 ) = 100
x - 6 - 43 = 100
x - 49 = 100
x = 149
[ ( 6x - 39 ) : 3 ] . 28 = 5628
( 6x - 39 ) : 3 = 201
6x - 39 = 603
6x = 642
x = 107
Chúc em hok tốt
Study well
\(707-3.(x+3^4)=407\)
\(\Rightarrow\)\(707-3.(x+81)=407\)
\(\Rightarrow\)\(3.(x+81)=707-407\)
\(\Rightarrow\)\(3.\left(x+81\right)=300\)
\(\Rightarrow\)\(\left(x+81\right)=300:3\)
\(\Rightarrow\)\(\left(x+81\right)=100\)
\(\Rightarrow\) \(x=100-81\)
Xin lỗi vì tôi có việc bận nên tí nữa sẽ làm tiếp
\(\Rightarrow\) \(x=19\)
A=1.1+2.2+3.3+.....+100.100
A=1.(2-1)+2.(3-1)+.......+100.(101-1)
A=1.2+2.3+......+100.101-1-2-3-4-.......-100
3A=1.2.(3-0)+2.3.(4-1)+......+100.101.(102-99)-(1+2+3+....+100).3
3A=1.2.3+2.3.4+....+100.101.102-1.2.3-2.3.4-.....-99.100.101-(1+2+3+......+100).3
3A=100.101.102-101.100.3
3A=101.100.(102-3)
3A=101.100.99
A=101.100.33
A=(mấy tự tính)
số sh cua tong A bang so hang cua day so cach deu 1 don vi tu 1 den 60
so sh cua tong A la:(60-1):1+1=60 (sh)
Cu 3 sh lien tiep cua tong A nhom thanh 1 nhom thi ta duoc so nhom la : 60: 3=20(nhom)
khi do : A = (2+2^2+2^3)+(2^4+2^5+2^6)+(2^7+2^8+2^9)+....+(2^58+2^59+2^60)
A=(2+2.2+2.2^2)+(2^4+2^4.2+2^4.2^2)+(2^7+2^7.2+2^7.2^2)+.....+(2^58
2^58.2+2^58.2^2)
A=2(1+2+2^2)+2^4(1+2+2^2)+2^7(1+2+2^2)+...+2^58(1+2+2^2)
A=2.7+2^4.7+2^7.7+...+2^58.7
A=7(2+2^4+2^7+...+2^58)
Vi 7 chia het cho 7
2+2^4+2^7+...+2^58 thuoc N
Suy ra 7(2+2^4+2^7+...+2^58) chia het cho 7
hay A chia het cho 7
Vay A chia het cho 7
Câu 1:
abc >/ 100 ; bca >/ 100 ; cab>/100
< = > abc + bca + cab >/300
< = > abc + bca + cab >/ 111
B=1+4+4^2+4^3+......+4^100
4B=4+4^2+4^3+4^4+........+4^101
4B - B = 4^101-1
3B=4^101-1
B=(4^101-1):3